 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.expressions;

 import org.w3c.dom.Element ;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;

 import org.eclipse.core.expressions.EvaluationContext;
 import org.eclipse.core.expressions.EvaluationResult;
 import org.eclipse.core.expressions.ExpressionInfo;
 import org.eclipse.core.expressions.IEvaluationContext;

 public class WithExpression extends CompositeExpression {

     private String fVariable;
     private static final String ATT_VARIABLE= "variable"; //$NON-NLS-1$

     /**
      * The seed for the hash code for all with expressions.
      */
     private static final int HASH_INITIAL= WithExpression.class.getName().hashCode();
     
     public WithExpression(IConfigurationElement configElement) throws CoreException {
         fVariable= configElement.getAttribute(ATT_VARIABLE);
         Expressions.checkAttribute(ATT_VARIABLE, fVariable);
     }

     public WithExpression(Element element) throws CoreException {
         fVariable= element.getAttribute(ATT_VARIABLE);
         Expressions.checkAttribute(ATT_VARIABLE, fVariable.length() > 0 ? fVariable : null);
     }

     public WithExpression(String variable) {
         Assert.isNotNull(variable);
         fVariable= variable;
     }

     public boolean equals(final Object object) {
         if (!(object instanceof WithExpression))
             return false;
         
         final WithExpression that= (WithExpression)object;
         return this.fVariable.equals(that.fVariable) && equals(this.fExpressions, that.fExpressions);
     }
     
     protected int computeHashCode() {
         return HASH_INITIAL * HASH_FACTOR + hashCode(fExpressions)
             * HASH_FACTOR + fVariable.hashCode();
     }

     public EvaluationResult evaluate(IEvaluationContext context) throws CoreException {
         Object variable= context.getVariable(fVariable);
         if (variable == null) {
             throw new CoreException(new ExpressionStatus(
                 ExpressionStatus.VARIABLE_NOT_DEFINED,
                 Messages.format(ExpressionMessages.WithExpression_variable_not_defined, fVariable)));
         }
         return evaluateAnd(new EvaluationContext(context, variable));
     }

     public void collectExpressionInfo(ExpressionInfo info) {
         ExpressionInfo other= new ExpressionInfo();
         super.collectExpressionInfo(other);
         if (other.hasDefaultVariableAccess()) {
             info.addVariableNameAccess(fVariable);
         }
         info.mergeExceptDefaultVariable(other);
     }
 }
